It is well documented that the elderly and post-surgical patients are at a heightened risk of falling. These individuals are often afflicted by gait and balance disorders, weakness, dizziness, confusion, visual impairment, and postural hypotension (i.e., a sudden drop in blood pressure that causes dizziness and fainting), all of which are recognized as potential contributors to a fall. Additionally, cognitive and functional impairment, and sedating and psychoactive medications are also well recognized risk factors.
A fall places the patient at risk of various injuries including sprains, fractures, and broken bones—injuries which in some cases can be severe enough to eventually lead to a fatality. Of course, those most susceptible to falls are often those in the poorest general health and least likely to recover quickly from their injuries. In addition to the obvious physiological consequences of fall-related injuries, there are also a variety of adverse economic and legal consequences that include the actual cost of treating the victim and, in some cases, caretaker liability issues.
In the past, it has been commonplace to treat patients that are prone to falling by limiting their mobility through the use of restraints, the underlying theory being that if the patient is not free to move about, he or she will not be as likely to fall. However, research has shown that restraint-based patient treatment strategies are often more harmful than beneficial and should generally be avoided—the emphasis today being on the promotion of mobility rather than immobility. Among the more successful mobility-based strategies for fall prevention include interventions to improve patient strength and functional status, reduction of environmental hazards, and staff identification and monitoring of high-risk hospital patients and nursing home residents.
Of course, direct monitoring of high-risk patients, as effective as that care strategy might appear to be in theory, suffers from the obvious practical disadvantage of requiring additional staff if the monitoring is to be in the form of direct observation. Thus, the trend in patient monitoring has been toward the use of electrical devices to signal changes in a patient's circumstance to a caregiver who might be located either nearby or remotely at a central monitoring facility, such as a nurse's station. The obvious advantage of an electronic monitoring arrangement is that it frees the caregiver to pursue other tasks away from the patient. Additionally, when the monitoring is done at a central facility a single person can monitor multiple patients which can result in decreased staffing requirements and/or more efficient use of current staff.
Generally speaking, electronic monitors work by first sensing an initial status of a patient, and then generating a signal when that status changes, e.g., he or she has sat up in bed, left the bed, risen from a chair, etc., any of which situations could pose a potential cause for concern in the case of an at-risk patient. Electronic bed and chair monitors typically use a pressure sensitive switch in combination with a separate electronic monitor which conventionally contains a microprocessor of some sort. In a common arrangement, a patient's weight resting on a pressure sensitive mat (i.e., a “sensing” mat) completes an electrical circuit, thereby signaling the presence of the patient to the microprocessor. When the weight is removed from the pressure sensitive switch, the electrical circuit is interrupted, which fact is similarly sensed by the microprocessor. The software logic that drives the monitor is typically programmed to respond to the now-opened circuit by triggering some sort of alarm—either electronically (e.g., to the nursing station via a conventional nurse call system) or audibly (via a built-in siren) or both. Additionally, many variations of this arrangement are possible and electronic monitoring devices that track changes in other patient variables (e.g., wetness/enuresis, patient activity/inactivity, bed-exit, temperature, position, etc.) are available for some applications.
General information relating to mat-type sensors, electronic monitors and other hardware for use in patient monitoring is relevant to the instant disclosure and may be found in U.S. Pat. Nos. 4,179,692, 4,295,133, 4,700,180, 5,600,108, 5,633,627, 5,640,145, and, 5,654,694, U.S. patent application Ser. Nos. 10/701,581 and 10/617,700, U.S. Pat. Nos. 6,111,509, 6,441,742, and U.S. patent application Ser. No. 10/210,817 (the last three of which concern electronic monitors generally). Additional information may be found in U.S. Pat. Nos. 4,484,043, 4,565,910, 5,554,835, 5,623,760, 6,417,777, U.S. patent application 60/488,021, (sensor patents) and U.S. Pat. No. 5,065,727 (holsters for electronic monitors), the disclosures of all of which aforementioned patents are all incorporated herein by reference as if fully set out at this point. Further, U.S. Pat. No. 6,307,476 (discussing a sensing device which contains a validation circuit incorporated therein), U.S. Pat. No. 6,544,200, (for automatically configured electronic monitor alarm parameters), U.S. Pat. No. 6,696,653 (for a binary switch and a method of its manufacture), and U.S. patent application Ser. No. 10/125,059 (for a lighted splash guard) are similarly incorporated herein by reference.
Additionally, sensors other than mat-type pressure sensing switches may be used in patient monitoring including, without limitation, temperature sensors, patient activity sensors, patient location sensors, bed-exit sensors, toilet seat sensors (see, e.g., U.S. Pat. No. 5,945,914), wetness sensors (e.g., U.S. Pat. No. 6,292,102), decubitus ulcer sensors (e.g., U.S. Pat. No. 6,646,556), restraint device sensors (e.g., U.S. patent application No. 60/512,042), etc., all of which are incorporated herein by reference. Thus, in the text that follows the terms “mat” or “patient sensor” should be interpreted in its broadest sense to apply to any sort of patient monitoring switch or device, whether the sensor is pressure sensitive or not.
Finally, pending U.S. patent application Ser. No. 10/397,126, discusses how white noise can be used in the context of decubitus ulcer prevention and in other contexts, and U.S. patent application Ser. No. 60/543,718 teaches the use of medical feedback systems to reduce the risk of decubitus ulcer formation. Both of these references are similarly fully incorporated herein by reference.
Of particular importance for purposes of the instant disclosure are those patient monitors that contain audible alarms that are adjustable in volume. Those of ordinary skill in the art will recognize that it is desirable in many settings to control the local alarm volume of the monitor depending on, among other things, the level of ambient noise, the distance to the caregiver, etc. However, conventionally the hardware that makes up such volume controls (e.g., potentiometers, digital potentiometers, etc.) is expensive and/or prone to failure either by physical damage or internal corrosion.
Heretofore, as is well known in the patient monitoring arts, there has been a need for an invention to address and solve the above-described problems. Accordingly, it should now be recognized, as was recognized by the present inventors, that there exists, and has existed for some time, a very real need for a system for monitoring patients that contains an adjustable volume alarm with the features described hereinafter.
Before proceeding to a description of the present invention, however, it should be noted and remembered that the description of the invention which follows, together with the accompanying drawings, should not be construed as limiting the invention to the examples (or preferred embodiments) shown and described. This is so because those skilled in the art to which the invention pertains will be able to devise other forms of this invention within the ambit of the appended claims.